The present invention relates to a device for applying radiation to an object under adjustable angles of incidence while maintaining the point of impingement of the beam constant, a reflection element being arranged in front of the object in order to deflect the radiation incident from a predetermined direction.
Such a device is used, for instance, in monochromators in which the object to be acted on by the radiation is developed as a dispersion element. This dispersion element is turnable, for selection of the wavelength, around an axis fixed in space which lies in the optically active surface. In order to maintain the optical conditions the same in every operating condition and thus avoid errors, it is necessary that the radiation, regardless of the angle of incidence, strike very precisely on the axis of rotation which is fixed in space, i.e. that the point of impingement of the beam remains constant.
This purpose can be achieved, in principle, by a rotation and simultaneous translation of the deflection element. Since both movements must be carried out with a high degree of precision, such a solution results in a very large expense for precision equipment.
It is also conceivable to provide a plurality of deflection elements each of which has a fixed location and angular position, which can be brought alternately into the beam path. Aside from the fact that a continuous change of the angle of incidence is not possible in such case, such a device is also very expensive and entails additional absorption.